Vehicles are equipped with driving mechanisms, such as internal-combustion engines, which comprise a number of sliding members (e.g., cams and camshafts, cylinders and pistons, and various shafts and bearings). In the machines comprising such sliding members (sliding machines), it is strongly demanded to reduce the friction coefficient between the sliding members to reduce the frictional loss or the like.
To this end, it has been proposed to form each sliding surface with an amorphous carbon film referred to as a diamond-like carbon film (which may be referred to as a “DLC film”) capable of reducing the friction coefficient, for example. Relevant descriptions are found in Patent Literatures 1-4 below.